Adding new LTO APIs to parse metadata nodes and extract linker options and
dependent libraries from a bitcode module.

Differential Revision: http://llvm-reviews.chandlerc.com/D2343



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199759 91177308-0d34-0410-b5e6-96231b3b80d8